1. Field of the Invention
The present invention relates to an automatic machine for bending connectors of micro chips having integrated circuits for connection of these circuits to a printed circuit on a substrate support.
2. Background of the Invention
Electronic equipment frequently utilizes assemblies for the handling of information which incorporates open integrated circuits mounted to circuit boards. These open integrated circuits may be in the form of chips or micro chips which are usually of rectangular or square shape with their sides measuring several milllimeters.
To facilitate the handling of these chips which are very small in size and to facilitate their control during mounting to a connection substrate having printed circuits thereon, these chips are mounted on an insulating support such as a flexible ribbon of inextensible insulating material provided with laterally regularly spaced perforations which enables it to be driven between operating stations by suitable processing apparatus. Equidistant openings are at the center of the ribbon over which the chips are located. These chips are maintained in the openings by an assembly of conductors which are disposed fan-wise around each of them and which are connected between contact points on the chip and the insulating support while sustaining each chip in the opening to which it corresponds. Generally, to obtain the conductors which connect the points with the edges of the openings in the support or insulating ribbon, a ribbon of copper of several hundred millimeters thickness is laminated on a ribbon in which the openings have been already cut. In each of these windows, the conductive ribbon of copper is etched, for example, chemically, in such a way as to leave only conductive bands which form the aforesaid conductors. These conductors extend to the edges of each window and abut the points of the integrated circuit chip or wafer placed at the center of the opening. Each extremity of these conductors is soldered to one of the connection points of the chip under consideration. It follows that the chips are thus solidly connected to the ribbon serving as a support and, when it is desired to detach one of the chips from their ribbon it is only necessary to cut the conductors which connect it to the ribbon at a certain distance from its edges, after a preliminary bending of the conductors. This bending of the conductors forms connectors that facilitate the connection of the chips on a connection substrate whichin itself is a delicate operation. Generally, to avoid during this operation the preliminary detachment of the extremities of the conductors soldered to the points of each chip from these points, it is known to provide on each of the conductors near the edge of each opening in the ribbon a structure for decreasing the mechanical stresses to which the conductors are subjected. This stress reducing structure is constituted, for example, by a ring which absorbs the forces of elongation to which the conductors are subjected during bending. Connection points are formed in each portion of the conductor which extend between the corresponding ppooooints of the chip and the neighborhood of the structure for decreasing the mechanical forces.
It is known to bend the conductors by means of an automatic machine which comprises a bending base and movable bending means situated with respect to this base. Generally, when the chip support is a ribbon, this ribbon is preliminarily cut at regular intervals between the chips in such a way that each portion of the ribbon thus obtained has an opening at the center at which is located the chip. This portion of the ribbon is then fixed in a body, and the bending of the connectors of the chips is then carried out by presenting each portion including the opening over which the chip is supported in the bending machine. In this machine, means are provided for displacing the chip support so as to move this chip on to the base in a perpendicular direction to the chip and to remove the chip from the base after bending. In this type of machine, mechanical means comprising a steel ram, for example, positions and maintains the chip in position on the base during the bending operation. Movable matrices curve the conductors in such a way as to form the contacts in a direction perpendicular to the chip.
This type of machine has numerous disadvantages. Firstly, it is necessary to cut the ribbon supporting the chips in regular portions so that each includes a chip having conductors which are to be bent to form the contacts. Each of these portions should be, before bending, properly inserted in a body and it is only after this mounting that the contacts of each of the chips are bent. These operations require careful manipulation and are slow and do not permit the bending operations to be carried out in long series. Another inconvenience results from the fact that the chips are positioned and maintained during the bending opration by a metallic ram which bears on the surface of the chip. This risks damage to the integrated circuits on each chip. Finally, in this type of machine, the bending matrices may damage the solder connections between the extremities of the conductors and the contact points of the chip because the solder connections are subjected to forces which could destroy them. These forces are only partially absorbed by the force reducing structures mentioned above.